Zane's parents, Kye Gbangbola and Nicole Lawler, were also taken ill at the family home just before 3.30am yesterday.

They remain in a serious but not life-threatening condition at St Peter's Hospital.

Two police officers and 13 nearby residents were released after being treated in hospital as a precaution.

Neighbour Anoop Hothi, 31, taught Zane martial arts at the Sport Martial Arts Academy in Egham, which Zane joined when he was five.

After just a year, the youngster became a member of the leadership team and last month he was promoted to green stripe belt.

Mr Hothi said: "Little Zane was an absolute joy to teach, and it's children like him who make teaching so much more rewarding.

"I'm sure his school teachers would say the same thing. He was a lovely boy, and he came from good, caring parents.

He criticised various agencies for their response to the floods in the area as he praised Zane's parents as the nicest neighbours he had ever had.

"It's not the parents who are to blame for this. They were loving and caring people - it's the overall system that's to blame for his death.

"Zane had his whole life ahead of him. It's heart-breaking for his parents. I found out yesterday morning and I didn't want to believe it."

"It was only a few months ago that my little brother was playing with Zane, and now he is in tears."

PA

Kye Gbangbola pictured clearing flood waters from outside his home near Chertsey, Surrey

Mr Hothi said he saw some pipes coming out from the front of Zane's parents' property throwing out water, but he did not know whether a generator was being used.

Last night it was revealed Zane's mother is a member of the All Party Parliamentary Climate Change Group and had recently warned government cuts had “affected planning, maintenance and the capacity to respond to incidents” when it came to flooding.

His father is the founder of a sustainability consultancy and the acting chairman of the Sickle Cell Society, set up in 1979 to highlight the plight of those with the genetic blood disorder.

A message on the Facebook page of Sport Martial Arts Academy announced Zane's death to members.

It said: "Many of you will know him and his parents and many of the children would have trained with him over the last two years that he has been with us.

"Starting off in Little Samurais aged five, he was always enthusiastic and energetic about his training, showing the same passion for martial arts that his father has.

"After a year he was a member of our leadership team helping and teaching others new to the club. Just last month he was promoted to green stripe belt."

Police and fire officers wearing white face masks entered the property today as it remained surrounded by floodwater from the River Thames.

Meanwhile, further tributes continued to pour in for Zane online.

One post on Facebook said: "Zane always had a smile on his face, he was so talented. RIP Zane, our thoughts are with his family."

Another said: "Our words are not adequate to express the sorrow we feel for Zane's family and the loss of such a wonderful boy.

"Zane was an inspiration to everyone around him. I imagine there is no pain more far-reaching and deeper than losing a child.

"Our hearts and prayers go out to his family at this most difficult time."

Officers have refused to be drawn on whether carbon monoxide poisoning from a generator pumping out flood water from his home may have been to blame.

Nicole Lawler mother of Zane Gbangbola

Chief Superintendent Dave Miller, of Surrey Police , said that the cause of Zane's death was still unknown, adding that it could be days before the exact cause was established and it would be "inappropriate" to speculate on what it might be.

He said: "The investigation into yesterday's tragic death of the seven-year-old boy is ongoing and the cause of death is still unknown.

"We are continuing to work with partner agencies and officers are following various lines of enquiry."

Mr Miller said that there did not appear to be a wider risk to the public.

"There have been no further casualties reported. This, coupled with expert advice, leads us to believe at this stage that this is an isolated incident localised to one family," he said. "Surrey Police will release an update when a cause of death has been determined, however this may take several days.

"Our thoughts continue to be very much with the boy's parents, who still remain in hospital, and we are continuing to support them during what is understandably a very difficult time."

Public Health England also said it did not believe there was a wider health risk to the public after nearby residents were evacuated and advised to go to hospital as a precaution.

A spokeswoman for the Department of Health agency, which is tasked with improving the nation's health, said it was helping police with their investigation.

"It is too early to speculate on the cause of death and Public Health England is working with the other agencies to assist this investigation and ensure appropriate action is taken to protect public health.

"Currently, there are no indications that there is a wider public health risk."

A South East Coast Ambulance spokeswoman said Zane was found to be in a "very serious condition" when crews arrived.

She said she could not be drawn on the suggestions that carbon monoxide poisoning was to blame.